Fuel is becoming increasingly more expensive. Also, fuel refinery is associated with the generation of pollutants and global warming. There is an increasing need in the industry to find cheaper, safer, and more environmentally unharmful ways to generate fuels. The development of means to produce fuel from biological material is an essential component of the future energy landscape. One of the most important elements in the production of fuel from biologic materials is the ability to digest or reduce certain molecular structures, such as cellulose, to molecular species recognizable as substrate for fuel generating processes, such as fermentation.
Molecular biology and genetic engineering hold promise for the production of large quantities of biologically active molecules that can be used to produce such fuels. For example, production of enzymes capable of breaking down organic materials into fuels hold promise to address the increasing needs for alternative fuels. A primary advantage of using genetic engineering techniques for producing such enzymes is that the methods allow for the generation of large amounts of a desired protein. In many cases, the only other way to obtain sufficient quantities of biological materials from non-engineered secretion sources is by purifying the naturally occurring biological material from cells of an organism that produce the agent. Thus, prior to the advent of genetic engineering, enzymes capable of degrading organic materials could only be isolated by growing the organism, typically a bacterial or fungal species, in large quantities and extracting the protein. Such procedures are often complex and economically prohibitive for use in fuel production.
Although genetic engineering provides a means to produce large amounts of a biological material, particularly proteins and nucleic acids, there are limitations to currently available methods. Bacteria provide an environment suitable to the production of such enzymes; however, byproducts produced by some bacteria would contaminate fuel sources. Thus, even where bacteria can be used to produce the biological material, additional steps such as purification or refining may be required to obtain biologically active material and/or bio-fuel. Furthermore, the use of non-photosynthetic systems requires the addition of costly sugar or other organic carbon sources to feed the recombinant organism. Additionally, there is typically a large capital investment associated with building fermenters.
Recombinant proteins also can be produced in eukaryotic cells, including, for example, fungi, insect cells and mammalian cells, which may provide the necessary environment to process an expressed protein into a biologically active agent. However, these systems typically suffer from the same cost prohibitions (sugar/organic carbon sources and fermenters). Thus, a need exists for methods to conveniently produce enzymes that are biologically active, can produce large quantities of enzymes and/or provide a host organism which is compatible with production of degradative enzymes.